Principal axis may refer to:
- Principal axis (mechanics)
- Aircraft principal axes
- Principal axis theorem
- Principal axes of a Matrix
- Principal axis (crystallography)
- Optical axis
Famous quotes containing the words principal and/or axis:
“Rather than have it the principal thing in my son’s mind, I would gladly have him think that the sun went round the earth, and that the stars were so many spangles set in the bright blue firmament.”
—Thomas Arnold (1795–1842)
“Our security depends on the Allied Powers winning against aggressors. The Axis Powers intend to destroy democracy, it is anathema to them. We cannot provide that aid if the public are against it; therefore, it is our responsibility to persuade the public that aid to the victims of aggression is aid to American security. I expect the members of my administration to take every opportunity to speak to this issue wherever they are invited to address public forums in the weeks ahead.”
—Franklin D. Roosevelt (1882–1945)